New Zealanders might believe they live in an egalitarian nation but a worldwide "better life index" shows the quality of life here is being significantly harmed by the gap between the richest and poorest.

New Zealand scored "exceptionally high" on the latest Better Life Index - a measure of a range of 11 categories compiled for 36 nations by the Organisation for Economic Cooperation and Development (OECD).

But in discussing New Zealand the OECD says that while the nation performs "exceptionally well in overall well-being" it is a question of money and how it is shared.

"Money, while it cannot buy happiness, is an important means to achieving higher living standards," the report says.

New Zealand's average household net-adjusted disposable income is US$21,892 a year (NZ$27,077.34), less than the OECD average of US$23,047.

"But there is a considerable gap between the richest and poorest - the top 20 per cent of the population earn five times as much as the bottom 20 per cent," the report says.

People in New Zealand work slightly less than the OECD average while 13 per cent of employees "work very long hours", more than the OECD average of 9 per cent.

New-Zealand is a top-performing country in terms of the quality of its educational system.

"The average student scored 524 in reading literacy, maths and science in the OECD's Programme for International Student Assessment," the study says.

New Zealand is one of the strongest OECD countries in students' skills.

On average in New Zealand, girls outperformed boys by 15 points, higher than the average OECD gap of 9 points.

New Zealand is average for life expectancy, has cleaner air and does well in terms of water quality.

The OECD says there is a strong sense of community and high levels of civic participation in New-Zealand, where 93 per cent of people believe that they know someone they could rely on in time of need, the report says.

"In general, 83 per cent of people in New-Zealand say they have more positive experiences in an average day (feelings of rest, pride in accomplishment, enjoyment, etc) than negative ones (pain, worry, sadness, boredom, etc) - more than OECD average of 80 per cent," it says.

In New Zealand, 92 per cent of people say they are satisfied with their housing situation, more than the OECD average of 87 per cent."

On crime the OECD says assault rates in all 36 countries have generally declined in the past five years.

In New Zealand, 2.2 per cent of people reported being assaulted over the previous 12 months, less than the OECD average of 4 per cent.

The homicide rate (the number of murders per 100,000 inhabitants) is a more reliable measure of a country's safety level because, unlike other crimes, murders are usually always reported to the police, the report says.

"New Zealand's homicide rate is 0.9, lower than the OECD average of 2.2. In New Zealand, the homicide rate for men is 1.1 compared with 0.7 for women," it says.

In New Zealand, 81 per cent of people feel safe walking alone at night, higher than the OECD average of 67 per cent.